This invention relates generally to the art of foam production and more particularly to a nozzle construction for generating a foamed liquid and to the process for generating such a foamed liquid.
As utilized within this disclosure the term "foam," "foamed liquid" and "foaming" relate to the conversion of a liquid substance to a substantially homogeneous mixture of that liquid with a gaseous substance. Generally, the gaseous substance is air and the liquid is converted into a film-like cellular structure encompassing that air. Foam has substantially different flow properties from a liquid and is thus useful to the extent that the different flow characteristics of the foam enhance the useful features of the liquid.
A particular area where a foam has been found useful is with detergent products such as those utilized for the cleaning of vertical surfaces such as windows and household woodwork. A foam possesses an advantage in that it is more readily visible than the homogeneous liquid by itself. Additionally, a foam product tends to stabilize on a vertical surface to an extent which is significantly greater than that of a homogeneous liquid. A homogeneous liquid to the contrary rather than stabilizing tends to quickly run off a vertical surface.
Another advantage for the utilization of a foam product is in the application thereof to the surface to be cleaned. Normally such detergent products are applied by projecting a stream of a liquid product to the surface. If a vertical surface is being utilized, a homogeneous liquid applied as a spray has a propensity to bounce off the surface and generally become airborne, whereas a foamed product tends to strike the vertical surface and remain as a foam upon that surface.
Various prior art devices have been devised for the production of foam. Generally such devices relate to techniques involving the mixing of air and the product to be foamed. A great deal of effort has been utilized in the production of foam for fire extinquishing purposes. There is, thus, a large body of patent literature related to highly mechanized and automated devices for the production of large volumes of foam. For example, there are many devices of the type utilized in the aviation industry for prevention of fires upon the landing of disabled aircraft. Various other industrial devices exist which utilize automated and high pressure equipment for the generation of foam. Examples of such devices are described in U.S. Pat. Nos. 3,446,285 and 3,547,200 to Hout; U.S. Pat. No. 3,094,171 to Gagliardo; U.S. Pat. No. 2,630,183 to Foutz; U.S. Pat. No. 2,624,622 to Holte; U.S. Pat. No. 3,388,868 to Watson et al; U.S. Pat. No. 3,784,111 to Piggott; and U.S. Pat. No. 3,701,482 to Sachnik.
Various nozzles exist within the prior art for atomizing a liquid for the purpose of producing a very fine spray as opposed to a foam. Examples of such prior art devices are found in U.S. Pat. No. 3,512,719 to Phelps et al and U.S. Pat. No. 4,187,985 to Goth.
Patents particularly directed to the production of foam from liquid detergent products are described in U.S. Pat. Nos. 3,918,647 to Lamz et al; 3,946,947 to Schneider and U.S. Pat. No. 4,013,228 also to Schneider. The nozzles disclosed in the above U.S. Patents relate to adjustable nozzles which are utilized with a very high pressure drop between the liquid and the foaming nozzle tip for use with manually operated pumping devices. The foam production section of the apparatuses described in the above patents is of significant length in comparison to a manually maneuvered container for the liquid detergent product. With the existence of all of these prior art devices, however, there is no single foam producing unit which is readily adaptable to use from the standpoint of manual force required to produce a foamed product together with an aesthetic appearance of the device and the quality of the foam produced.